1. Field of the Invention
The present invention relates to inhibition of protein kinases. In particular, the present invention relates to therapeutic uses of polypeptides that inhibit protein kinases.
2. Description of Related Art
The inventions described herein arose from the pioneering work of Sanders, which documented the antipolio action of detoxified venoms from Elapidae. His work was preceded by the original observations of Bodian and Howe (Bull. Johns Hopkins Hospital, 69: 79-85 (1941)) that proved and measured the retrograde axonal transport of polio viruses to the central nervous system. The latter phenomenon was accomplished by severance of the sciatic nerve in rats at different times following viral infection of the footpads distal to the severed nerves. Sanders was also cognizant of the early studies, by Lamb and Hunter (Lancet, 1: 20-22 (1904)), of the pathology of cobra bites in patients in India, and in experimental animals injected with those venoms. Changes in structures within higher centers of the CNS, including central chromatolysis, occurred within 1-4 hours following cobra envenimation. Further, it was long recognized from clinical observations that rabies viruses, and proteins such as tetanus toxin (Wright et al., Brit. J. Expl. Path. 32: 169 (1951)), appeared to travel to the central nervous system via nerve pathways. From those and other observations Sanders initiated his extensive studies into the ability of neurotoxic snake venoms, detoxified by a specific chemical means, to prevent polio infections in mice, rats and monkeys challenged with poliovirus preparations (Sanders, et al., Ann. N.Y. Acad. Sci. 58: 1-12 (1953)). Those studies were based on what was known at the time as the “interference” phenomenon in which infection with one virus conveys resistance to a second virus acquired a short time later.
With the availability of the Salk vaccine in the early 1950's Sanders polio work was discontinued. He then initiated studies into effects of his medicines on the progressive, irreversible neuromuscular dysfunctions in patients with amyotrophic lateral sclerosis (ALS). His clinical studies employed a Time-Series protocol, the statistical means with which to evaluate drug effects in patients such as those with ALS. By that means he circumvented the ethical problem of placebo administration to patients with a progressive, irreversible disease.
The realization that protein toxins bind strongly to specific receptors on target cells surged with the discovery, by van Heyningen and Miller (J. Gen. Microbiol., 24: 107 (1961)), that tetanus toxin binds strongly to gangliosides, chemical constituents of nerve cells. That phenomenon initiated wide-ranging investigations by biochemists into the strong affinities many protein toxins exhibit toward their specific receptors on cells. Further, they identified nontoxic fragments from within the respective protein toxins that retained the cell-binding functions. Such nontoxic, cell-binding fragments offer potential therapeutic and diagnostic opportunities, the goals of many subsequent studies. In 1977 Miller et al., employing separations technology, identified the alpha-neurotoxins in the venoms as precursors of the active principals in Sander's medicine (Biochim. Biophys. Acta, 496: 192-196 (1977)). Exploitation of the phenomenon quickly followed. The amelioration of herpes virus infections in tissue culture systems and in experimental animals was defined by Yourist et al. (J. Gen. Virol., 64: 1475-1481 (1983)). Lentz et al., (Biochem., 30: 10949-10957 (1991)) identified constituents on rabies viruses that have amino acid sequences homologous with those in the alpha-neurotoxins. Similar structures also occur in the human immunodeficiency viruses (Bracci et al., Arch. Virol., 114: 265-268 (1990)), also a neurotropic virus.
The ability of the nontoxic peptide preparations to inhibit neurotropic viruses supported Sander's original hypothesis that neurotoxic venom constituents retain affinities for receptor sites on cells, providing one mechanism for the cell protection from those viruses. The surprising discovery that the same nontoxic derivatives of the animal neurotoxins also inhibit the neuraminidases of a number of myxoviruses (Miller and Austin, U.S. Pat. No. 7,259,237, herein incorporated by reference) assigns a second antiviral property to the same peptides. Viral neuraminidases are required for the release of newly formed myxovirus varions from their sites of origin.
The present invention now adds a third mechanism by which the same nontoxic toxin-derived peptides modulate biologic phenomena. They inhibit protein kinases such as those in heart muscle and human myelin as described below.